Asphalt compositions



ASPHALT COMPOSITIONS John A. Schmitt, Midland, Mich., assignor to Standard Oil Company, Chicago, Ill., a corporation of Indiana No Drawing. Application November 19,1956

' Serial No. 622,765 1 I 8 Claims. (Cl. 106-269) This invention relates to improvements in asphalts and more particularly relates to asphalts resistant to alligatoring.

One of the major types of failure of asphalts, especially roofing asphalts, is the phenomenon known as alligatoring brought about by the asphalt flowing or creeping underneath the surface skin and away from surface cracks. When films of asphalts are exposed to the atmosphere and sunlight, the shiny black surface becomes dull and chalky after a few days exposure. which occurs at the surface only is due to weathering. Certain weathering conditions contribute to so-called alligatoring; an asphalt susceptible to flow, direct sun- This change 1 light to furnish ultraviolet light, and a sufiiciently high posure, the surface film or skin may contract, and crack.

The sub-surface asphalt then slowly flows away from the cracks forming channels which eventually penetrate through the whole film and permit water leakage.

It is an object of the present invention to provide an asphalt composition which is resistant to alligatoring. Another object of the invention is to provide a roofing asphalt which does not tend to alligator. Still another object of the invention is to provide a method of inhibiting the tendency of asphalts to alligator. Other objects and advantages of the invention will become apparent from the following description thereof.

In accordance with the present invention, the above objects are attained by the use of asphalt containing from about 0.001% to about 1.0% preferably 0.05% to about 0.5% of an oil-soluble polyvalent metal soap of a high molecular weight mono-carboxylic acid of at least about 10, preferably 12 to about 30, carbon atoms. Examples of such soap are copper oleate, cobalt naphthenate, man- I ganese naphthenate, copper oleate, manganese stearate, copper laurate, etc. In using such fatty acid soap, itis important that they be used in amounts within the above limits, since the use of large amounts of the soap will promote too rapid hardening and result in failure from rupturing after embrittlement.

The effect of various materials on the alligatoring of asphalts is determined by an accelerated test in the Weather-Ometer, a commercial accelerated weathering device. The apparatus is equipped with a thermostatically controlled cabinet in which .a cylindrical panel holder rotates around a carbon-arc lamp. The use of special carbon rods and Corex-D filters gives a light which simulates intense sunlight, including the ultraviolet frequencies. The test panels, three-by-six-inch aluminum sheets with upturned edges, are coated with an 0.025 inch film by weighing out the calculated amount of asphalt and heating so that leveling occurs. Each cycle consists of 18 hours in the Weather-Ometer under thelight at a black bulb temperature of 175 F., followed by 2 hours 2,928,753 Patented Ma r.,15, 19 0 Failure is determinedwith a spark-gap instrument, de-

veloped by the ASTM, in which a high-voltage probe is passed over the weathered film. Wherever the film is broken a spark-through occurs. More than six such spark-through points, separated by at least inch, is the. criterion. of' failure. The number of Weather-Ometer cycles required to reach this stage is recorded as the accelerated life of the asphalt being tested. The extent of alligatoring is also noted.

The eifectiveness of the described metal soaps in preventing alligatoring is demonstrated by the data'in Table I, obtained in the above described test with the Weather-Ometer. tures so tested was an asphalt made largely from uncracked products and having the following specifications:

1 Not less than." i 2 Not more than."

Table I Cycles in Sample Metal Weather- Alligatoring No. Ometcr To Failure 1 N0ne (control) 12-15 Deep. 2 N o. 1 plus 0.05% copper oleate... 34 None. 3 N o.-1 plus 0.1% cobalt naphthe- 46 Do'.

11 e. 4. No. 1 plus 0.05% manganese 36 Dooleate.

The term asphalt as used herein and in the appended claims means normally solid asphaltic products and may be residual asphalts, steam-reduced asphalts, propane precipitated asphalts, oxidized asphalts, pressure still tars or mixtures thereof. While the specifications for such asphalts may vary depending upon locality, special specifications for particular uses, etc. in general the softening point, may vary from about F. to about 300 F.

Percentages given herein and in the appended claims are weight percentages unless otherwise stated.

I claim:

1. A non-alligatoring composition consisting essentially of a normally solid asphalt normally susceptible to alligatorin-g and from about 0.001% to about 0.5% of an oil-soluble polyvalent metal soap of a'high molecular weight monocarboxylic acid having at least ten carbon atoms, selected from thegroup consisting of a naphthenic acid and oleic acid, said polyvalent metal being selected from the group consisting of copper, cobalt, and manganese.

2. An asphalt composition as described in claim 1 in which the polyvalent metal soap is copper oleate.

3. An asphalt composition as described in claim 1 in which the polyvalent metal soap is manganese oleate.

4. A non-alligatoring asphalt composition consisting essentially of a major proportion of a normally solid asphalt, normally susceptible to alligatoring, and from about 0.001% to 0.5% cobalt naphthenate.

5. The method of inhibiting the alligatoring of a normally solid asphalt normally susceptible to alligatormg when exposed to sunlight and weathering comprising incorporating in said asphalt from about 0.001% to about 0.5 of an oil-soluble polyvalent metal soap of a The asphalt (control) use in the mix- 3 a high molecular weight monocarboxylic acid having at least 10 carbon atoms, selected from the group consist ing of a naphthenic acid and oleic acid, said polyvalent metal being selected from the group consisting of copper, cobalt and manganese.

6. The method of claim 5. in which the polyvalent metal soap is copper oleate.v

7. The method of claim 5 in which the polyvalent metal soap is manganese oleate.

8. The method of inhibiting the alligatoring of a normally solid asphalt, normally susceptible to alligatoring" when exposed to sunlight and weathering, comprising incorporating in said asphalt from about 0.001% to 0.5% cobalt naphthenate.

References Cited in the file of this patent UNITED STATES PATENTS Flood Dec. 3, 1935 Ken et a1. Feb. 6, 1940 Schiller Aug. 14, 1945 Agnew Nov. 11, 1947 Holmes Dec. 25, 1951 Fasoldet a1. Jan. 8, 1952 OTHER REFERENCES page 730. 

1. A "NON-ALLIGATORING" COMPOSITION CONSISTING ESSENTIALLY OF A NORMALLY SOLID ASPHALT NORMALLY SUSCEPTIBLE TO "ALLIGATORING" AND FROM ABOUT 0.001% TO ABOUT 0.5% OF AN OIL-SOLUBLE POLYVALENT METAL SOAP OF A HIGH MOLECULAR WEIGHT MONOCARBOXYLIC ACID HAVING A LEAST TEN CARBON ATOMS, SELECTED FROM THE GROUP CONSISTING OF A NAPHTENIC ACID AND OLEIC ACID, SAID POLYVALENT METAL BEING SELECTED FROM THE GROUP CONSISTING OF COPPER, COBALT, AND MANGANESE. 